The thesis deals with a four-storey building. The main part of the steel load-baring construction is represented by moment resisting frames that carry the entire vertical load and the horizontal load in the transverse direction. The secondary beams, together with the moment resisting frame columns form the four frames in the longitudinal direction. For the transfer of the horizontal loads in the longitudinal direction, three centric brace systems are placed on both outer frames. The internal forces for the ultimate limit states and displacements for the serviceability limit states are determined by the elastic global analysis, taking into account the second order analysis. The global imperfection is taken into account by a horizontal offset of the moment resisting frame. Seismic analysis is performed using latheral force method. The design is carried out in accordance with the rules for earthquake-resistant. The construction achieves a high ductility level. Fire resistance of the composite floor is defined with MACS+. The membrane effect in the functioning of the composite floor during a fire is taken into account.